(a) Field
The present invention generally relates to a device-to-device direction communication.
(b) Description of the Related Art
Recently, interest in a device-to-device (D2D) direct communication is increasing for providing a proximity-based service. Accordingly, various techniques for supporting the D2D direct communication are developed.
A wireless communication system such as a wireless local area network (WLAN) performs a carrier sensing for the D2D direct communication. The carrier sensing requires much high power and resource consumption. Particularly, if the number of devices increases, a probability with which a device occupies the resource decreases and a probability with which a collision occurs at the occupied resource increases. As a result, use efficiency of the resource is reduced.
A scheme for avoiding the collision with the other devices based on the carrier sensing has been developed. However, if the number of devices increases, signals for avoiding the collision occupies almost all of the resources, so the resources cannot be used for traffics to be transmitted.